Exclusive test ride. Amaury Pierron's 29" Commencal DH bike - Dirt

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Downhill Bikes

Exclusive test ride. Amaury Pierron’s 29″ Commencal DH bike

Works magic

Amaury Pierron’s Commencal 29”

Words and Images by Steven Jones and Nico Brizin

Back in March when I rode the prototype Trek 29” downhill bike in the hills east of Los Angeles I had little doubt that the big wheels would be a key part of the unfolding story of the World Cup season. A visit to Intense backed this up as Jeff Steber said it was finally time that the sport embraced a wheel size that holds solid evidence of the speed advantage.

In the off-season Santa Cruz had cobbled together a pretty workmanlike looking V10 with 29” wheels and in doing so rattled a few cages. In truth the 29” beast had bolted many years before Santa Cruz started shouting. Lourdes was a stir but downhill being downhill it seemed many riders were not prepared to cuddle up to a ride that had offered less fatigue. Roughing it was the way of the racer. And anyhow most brands had been caught napping.

At Lourdes it happened, the qualifier at least. Three 29” bikes in the top five from which point the pits had suddenly gained acceptance or seemed compelled into the way of the larger wheel. By Fort William Danny Hart had a Mondraker shod with 29” wheels and Commencal…..well it seemed they’d prepared for the swap already.

Gwin in the meantime was having none of it. Only a mistake and bad luck prevented him from winning Fort William and Lenzerheide. He took the title proving that it wasn’t about the wheels. But we knew that anyway.

However, at the end of the 2017 world cup calendar Amaury Pierron came within a second and a half of winning the season closer at Val Di Sole, heading up a three strong French rider podium along with Bruni and Vergier. It was the young Frenchman’s best ever result. To my total surprise I found myself riding his very bike in Andorra.

To begin, it’s not just about the wheel size, a bike must have good geometric principles regardless of what’s rolling down the hill. The 27.5 version of the bike surprised me in many ways when I rode it last year. Even though the sizing came up short, on paper it rode well, the short chainstay and rearward axle path working well with a suspension design that held the rider impressively well in the mid part of the travel – 220mm of it.

When I arrived in Andorra the world cup track was like a war zone. Without the time to work out the jigsaw we chose to ride some natural steep, rooty terrain that was mixed in with some flat out sections.

Jones working for it in the autumn dust
Snug but totally silent.
Guarded. But this aluminum bike can take a beating
Idler proved to be light on the hoof and silent
After the test we got to view the production version of Pierron's bike. Impressive. That man Nico Brizin. The next 24 hours were a blur

I was quickly re-acquainted with the crazy pace of a 29” wheel downhill bike on the fast open upper sections. The big wheels allow for better stability and efficiency through fast breakers. In such situations the bike is effortless to ride.

In terms of sizing the bike was a large and slightly too small, but Commencal say this is to become the size medium for 2018. I expect Pierron only to improve with this change.

What puzzles me is the ride dynamic in super steep sections. For sure riding the smaller wheels are marginally more comfortable in the super steep sections and possibly faster in certain sectors of a track like Vallnord. The main problem with the big 29” wheels is weight placement over the rear in that the wheel can sometimes be in the way. However the answer to this is probably more about adaption than it being a negative. What will also come into play is that any slight disadvantage will be made up by increases in other sections of the track. All told it’s a game of profit and loss with the 29” wheels.

The bike is impressive and on the fast sections a bike like this will blow your mind for out and out pace on big open sections. The only problem here is stopping the thing. Braking and 29” wheels is an art that really takes time to adapt to.

Fatigue levels were low, the all-aluminium bike working with you. There is good compliance in the wheelset chosen by Pierron. It really brings into focus and questions the performance advantage that many believe carbon fibre to have. To make a claim that carbon fibre is better is a daft generalisation and one that is hard to prove. The same could be said about making claims about 29” wheels. The bike has to be good from the get go.

What we know is this aluminium bike with 29” wheels delivers. Quiet, offering something special in design, prices will be good and Commencal have certainly stepped up the finish of the bikes for 2018. If the production black bike pictured is anything to go by 2018 will be the best that Commencal have produced to date. A bike that I enjoyed riding immensely.


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